In a competitive market, semiconductor device manufacturers need to minimize waste and consistently produce high quality semiconductor devices to maintain a competitive edge. Accordingly, tight control of the processing environment is advantageous to achieve optimal results during substrate processing. Thus, manufacturing companies have dedicated time and resources to identify methods and/or arrangements for improving substrate processing.
In order to provide tight control of the processing environment, characterization of the processing environment may be required. To provide the data needed to characterize the processing environment of a processing chamber, sensors may be employed to capture processing data during the execution of a recipe. The data may be analyzed and the processing environments may be adjusted accordingly (e.g., “to tune a recipe”).
Typically analysis is performed after a single substrate or a substrate lot has been processed. The measurement is usually performed offline by one or more metrology tools. The method usually requires time and skill to take the measurements and/or to analyze the measurement data. If a problem is identified, additional time may be required to cross-reference the measurement data with the processing data to determine cause of the problem. Usually, the analysis may be complex and may require expert human interpretation. Furthermore, the analysis is usually not performed until at least one, and probably several, substrates have been processed. Since the analysis is not performed in-situ and in real time, damage and or undesirable effects may have already occurred to the substrate(s) and/or the processing chamber/chamber parts.
In some plasma processing tools, the sensors may be integrated as part of the process control loop. Thus, the sensors not only collect processing data but may also be employed as a monitoring tool. In an example, a pressure manometer may be employed to collect pressure data. However, the data collected by the pressure manometer may be employed by the processing module controller to adjust the pressure set point, for example, during the execution of the recipe.
To facilitate discussion, FIG. 1 shows a simple block diagram of a processing chamber. The diagram is not meant to be an exact representation of a processing chamber. Instead, the diagram is meant to illustrate how a set of sensors may have been implemented within a processing chamber in order to facilitate the execution of a process recipe.
Consider the situation wherein, for example, a substrate lot is to be processed within a processing chamber 100. Prior to processing, metrology tool 102 (which may be one or more metrology tools) may be employed to perform pre-processing measurements. The pre-processing measurement data from metrology tool 102 may be uploaded via a link 104 to a fabrication facility host controller 106.
To begin processing a substrate lot, a user may employ fabrication facility host controller 106 to choose a recipe for execution. In some instances, the measurement data may be employed by fabrication facility host controller 106 to adjust the recipe set points in order to compensate for the incoming material differences. In an example, the pre-processing measurement data of a substrate may indicate that the physical characteristic of the substrate is different than what is expected by the recipe. As a result, the recipe set points may be adjusted to account for the known differences in the substrate.
Once the recipe has been chosen and the recipe has been adjusted based on the pre-measurement data, fabrication facility host controller 106 may send the recipe to a process module (PM) controller 108 via a link 110. A substrate 112 may be loaded into processing chamber 100. Substrate 112 may be positioned between a lower electrode 114 (such as an electrostatic chuck) and an upper electrode 116. During processing, a plasma 118 may be formed to process (e.g., etch) substrate 112.
During processing, a plurality of sensors may be employed to monitor the state of processing chamber 100, plasma 118, and/or substrate 112. Examples of sensors may include but are not limited to: a gas flow controller (120), temperature sensors (122 and 124), a pressure sensor (126), a set of match box controllers (128), a radio frequency (RF) controller (130), a valve controller (132), a turbo pump controller (134), and the like. In an example, pressure sensor 126 may be capturing pressure data within processing chamber 100. In another example, RF generator controller 130 and/or set of match box controllers 128 may be collecting data about reflective power, impedance, harmonics and the like.
The data collected by each of the sensors may be forwarded along communication lines (such as 140, 142, 144, 146, 148, 150, and 152) to a control data hub 136 for analysis. If any one recipe set point needs to be adjusted based on the analysis, control data hub 136 may send the result to process module controller 108 (via link 138) and process module controller 108 may adjust the recipe set point accordingly. In an example, the desired pressure set point according to the recipe may be set to 30 millitorrs. However, according to pressure sensor 126, the pressure measurement is actually 26 millitorrs. As a result, process module controller 108 may adjust a pressure control actuator to bring the pressure back to the desired recipe set point.
A uni-variate orthogonal control scheme is typical of a process control relationship implemented between recipe set points and sensors. In other words, a recipe set point may be associated with data collected from a single sensor which is considered to be only responsive to a single parameter. Data collected from any other sensor is usually not considered in determining whether a specific recipe set point is followed.
In the example above, the chamber pressure is adjusted based on the data provided by pressure sensor 126. In making the adjustment, process module controller 108 may be assuming that pressure sensor 126 is providing accurate data and that pressure sensor 126 is not suffering from drifts and/or part wear. However, if pressure sensor 126 has actually drifted, the increase in pressure by process module controller 108 in an attempt to bring the chamber condition back to the desired state may result in undesirable results on substrate 112, and abnormal conditions appertaining to the chamber walls and components therein (including the sensors themselves).